CN112081928A

CN112081928A - Electronic expansion valve

Info

Publication number: CN112081928A
Application number: CN201910508067.9A
Authority: CN
Inventors: 贺宇辰; 许学飞; 吴晗
Original assignee: Zhejiang DunAn Hetian Metal Co Ltd
Current assignee: Zhejiang DunAn Hetian Metal Co Ltd
Priority date: 2019-06-12
Filing date: 2019-06-12
Publication date: 2020-12-15
Also published as: JP7307808B2; KR20210142202A; KR102571453B1; JP2022536236A; US20220228784A1; EP3957881A1; WO2020248760A1; EP3957881A4

Abstract

The invention provides an electronic expansion valve, comprising: the valve comprises a shell, a valve body and a valve seat, wherein the shell is provided with a containing cavity and a valve cavity, the containing cavity and the valve cavity are arranged at intervals, the valve cavity is used for being communicated with a pipeline, the shell comprises the valve seat, and the valve cavity is arranged in the valve seat; the valve core assembly is movably arranged in the shell and provided with an opening position and a plugging position, when the valve core assembly is positioned at the opening position, the valve cavity is in a conducting state, and when the valve core assembly is positioned at the plugging position, the valve cavity is in a blocking state; the guide seat is arranged in the shell and located between the containing cavity and the valve cavity, the valve core assembly is partially arranged in the guide seat in a penetrating mode, a balance channel is arranged between the guide seat and the valve seat, one end of the balance channel is communicated with the containing cavity, and the other end of the balance channel is communicated with the valve cavity. Through the technical scheme that this application provided, can solve the problem that is difficult to realize quick pressure balance among the prior art.

Description

Electronic expansion valve

Technical Field

The invention relates to the technical field of electronic expansion valves, in particular to an electronic expansion valve.

Background

Currently, an electronic expansion valve includes a housing and a valve core assembly disposed within the valve body. The shell comprises an accommodating cavity and a valve cavity, the valve cavity is communicated with the pipeline, and the valve core assembly moves in the shell to adjust the communication condition of the valve cavity and the pipeline, so that the electronic expansion valve is opened and closed.

However, in the prior art, the accommodating chamber is not communicated with the valve chamber, and when the electronic expansion valve is opened or closed by using the valve core assembly, a pressure difference exists between the accommodating chamber and the valve chamber, so that the action performance of the valve core assembly is affected. Therefore, there is a problem in the prior art that it is difficult to achieve rapid pressure equalization.

Disclosure of Invention

The invention provides an electronic expansion valve, which aims to solve the problem that rapid pressure balance is difficult to realize in the prior art.

The invention provides an electronic expansion valve, which comprises: the valve comprises a shell, a valve body and a valve seat, wherein the shell is provided with a containing cavity and a valve cavity, the containing cavity and the valve cavity are arranged at intervals, the valve cavity is used for being communicated with a pipeline, the shell comprises the valve seat, and the valve cavity is arranged in the valve seat; the valve core assembly is movably arranged in the shell and provided with an opening position and a plugging position, when the valve core assembly is positioned at the opening position, the valve cavity is in a conducting state, and when the valve core assembly is positioned at the plugging position, the valve cavity is in a blocking state; the guide seat is arranged in the shell and located between the containing cavity and the valve cavity, the valve core assembly is partially arranged in the guide seat in a penetrating mode, a balance channel is arranged between the guide seat and the valve seat, one end of the balance channel is communicated with the containing cavity, and the other end of the balance channel is communicated with the valve cavity.

Further, the casing still includes the sleeve pipe, and the disk seat is connected with the sleeve pipe, and the disk seat one end that is close to the sleeve pipe has the mounting hole, and the mounting hole holds the chamber with the inside intercommunication of sleeve pipe in order to form, and the valve pocket sets up the other end at the disk seat, and the mounting hole is passed through to the one end of guide holder and disk seat fixed connection.

Furthermore, the valve core assembly comprises a nut seat and a screw rod penetrating through the nut seat, the other end of the guide seat is connected with the nut seat, and the outer wall of the guide seat is in transition fit or interference fit with the inner hole of the nut seat, so that the nut seat is guided, and the coaxiality among the nut seat, the screw rod and the valve seat is improved.

Further, the mounting hole is the shoulder hole, and the mounting hole is including setting up in order and the first hole and the second hole that the aperture reduces in proper order, second hole and valve pocket intercommunication.

Furthermore, the outer wall of the guide seat is provided with a limiting boss, the limiting boss is in interference fit with the first hole, the limiting boss is used for limiting the relative position of the guide seat and the valve seat, and the guide seat is arranged in the first hole and the second hole in a penetrating mode.

Further, the balance passage comprises a notch, the notch is arranged on the side wall of the limiting boss, and the accommodating cavity is communicated with the valve cavity through the notch.

Further, spacing boss includes first boss and the second boss that the ladder set up, and first boss corresponds first hole setting, and the second boss corresponds the second hole setting, and first boss and second boss are run through to the breach.

Furthermore, be provided with a plurality of breachs on the lateral wall of guide holder, a plurality of breachs are along the circumference interval setting of spacing boss.

Further, the guide seat and/or the valve seat are/is provided with a communication hole, one end of the communication hole is communicated with the accommodating cavity, the other end of the communication hole is communicated with the valve cavity, and the communication hole forms a balance channel.

Further, the intercommunicating pore is arranged on the limiting boss, one end of the intercommunicating pore is communicated with the accommodating cavity, and the other end of the intercommunicating pore is communicated with the second hole.

Further, the guide holder has a plurality of intercommunicating pores, and a plurality of intercommunicating pores are arranged on the spacing boss at intervals along the circumferential direction of the guide holder.

By applying the technical scheme of the invention, the electronic expansion valve comprises a shell, a valve core assembly and a guide seat. Wherein, the casing has and holds chamber and valve chamber, and the valve chamber is used for communicating with the pipeline. The valve cavity is switched between a conduction state and a blocking state by moving the valve core assembly between the opening position and the blocking position. Specifically, the guide seat is arranged between the accommodating cavity and the valve cavity, the balance channel is arranged between the guide seat and the shell, one end of the balance channel is communicated with the accommodating cavity, the other end of the balance channel is communicated with the valve cavity, so that the communication between the accommodating cavity and the valve cavity can be realized, when the electronic expansion valve is opened or closed, the accommodating cavity and the valve cavity can realize quick pressure balance through the balance channel, and further, the action performance of a valve core assembly in the expansion valve cannot be influenced.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic structural diagram illustrating an electronic expansion valve according to an embodiment of the present invention;

fig. 2 shows a partial enlarged view at a in fig. 1;

FIG. 3 is a schematic view of the guide shoe of FIG. 1;

FIG. 4 shows a further constructional schematic of the guide shoe of FIG. 1;

fig. 5 is a schematic structural diagram illustrating an electronic expansion valve according to a second embodiment of the present invention;

fig. 6 shows a partial enlarged view at B in fig. 5;

FIG. 7 is a schematic view of the guide shoe of FIG. 5;

fig. 8 is a schematic view showing another structure of an electronic expansion valve according to a second embodiment of the present invention;

fig. 9 shows a partial enlarged view at C in fig. 8;

fig. 10 shows a schematic structural view of the guide shoe in fig. 8.

Wherein the figures include the following reference numerals:

10. a housing; 11. an accommodating chamber; 12. a valve cavity; 13. a sleeve; 14. a valve seat; 141. a first hole; 142. a second hole;

20. a valve core assembly; 21. a rotor; 22. a nut seat; 23. a screw; 24. a valve needle assembly;

30. a guide seat; 31. a limiting boss; 311. a first boss; 312. a second boss;

40. a balancing channel; 41. a notch; 42. and a communicating hole.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 to 4, according to an embodiment of the present invention, there is provided an electronic expansion valve including a housing 10, a valve core assembly 20, and a guide seat 30. The housing 10 has a containing cavity 11 and a valve cavity 12, the containing cavity 11 and the valve cavity 12 are arranged at an interval, the valve cavity 12 is used for communicating with a pipeline, the housing 10 includes a valve seat 14, and the valve cavity 12 is arranged in the valve seat 14. The valve core assembly 20 is movably disposed in the housing 10, the valve core assembly 20 has an open position and a blocking position, when the valve core assembly 20 is located at the open position, the valve cavity 12 is in a conducting state, and when the valve core assembly 20 is located at the blocking position, the valve cavity 12 is in a blocking state. In this embodiment, the valve chamber 12 is connected to two conduits, and when the valve core assembly 20 is in the open position, the two conduits can be communicated through the valve chamber 12, and when the valve core assembly is in the blocking position, the two conduits are separated by the valve chamber 12. Specifically, the guide seat 30 is disposed in the housing 10, and the guide seat 30 is located between the accommodating chamber 11 and the valve chamber 12. A balance passage 40 is arranged between the guide seat 30 and the valve seat 14, one end of the balance passage 40 is communicated with the accommodating cavity 11, and the other end of the balance passage 40 is communicated with the valve cavity 12, so that the accommodating cavity 11 can be communicated with the valve cavity 12.

With the electronic expansion valve provided in this embodiment, the balance passage 40 is provided between the accommodating chamber 11 and the valve chamber 12, so that the accommodating chamber 11 can communicate with the valve chamber 12. When the valve core assembly 20 moves in the housing 10 to switch the valve cavity 12 between the conducting state and the blocking state, the accommodating cavity 11 and the valve cavity 12 can realize rapid pressure balance through the balance channel 40, so that the valve core assembly 20 cannot be damaged, the action performance of the valve core assembly is prevented from being influenced, and the service life and the reliability of the expansion valve can be further prolonged.

In this embodiment, the housing 10 further comprises a sleeve 13, the valve seat 14 is partially located in the sleeve 13, and the valve seat 14 is fixedly connected to the sleeve 13. Wherein, the valve seat 14 has a mounting hole at one end near the sleeve 13, and the guide seat 30 is fixedly connected with the valve seat 14 through the mounting hole. And the mounting hole is communicated with a sleeve 13 to form an accommodating cavity 11, a valve cavity 12 is arranged at the other end of a valve seat 14, the valve cavity 12 is used for being communicated with a pipeline, and a valve port is arranged in the valve cavity 12 and is arranged at the pipe orifice of one pipeline.

Specifically, the mounting hole is a stepped hole. In the present embodiment, the mounting holes include a first hole 141 and a second hole 142 which are sequentially arranged and whose diameters are sequentially reduced, and the second hole 142 communicates with the valve chamber 12.

Wherein, the outer wall of the guide seat 30 is provided with a limit boss 31. In this embodiment, the limiting boss 31 is in interference fit with the first hole 141 to realize the fixed connection between the guide seat 30 and the valve seat 14, so that the relative position between the guide seat 30 and the valve seat 14 can be limited by the limiting boss 31. Specifically, the guide holder 30 is inserted into the first hole 141 and the second hole 142. In this embodiment, the position of the limiting boss 31 is in interference fit with at least one of the first hole 141 and the second hole 142.

As shown in fig. 3 and 4, the balance passage 40 includes a notch 41, and the notch 41 is provided on a side wall of the limit projection 31. Specifically, one end of the notch 41 is communicated with the accommodating chamber 11, and the other end of the notch 41 is communicated with the valve chamber 12, so that the accommodating chamber 11 can be communicated with the valve chamber 12 through the notch 41. In this embodiment, the notch 41 is a cut surface, the cut surface is disposed through the limiting boss 31, and a gap exists between the cut surface and the mounting hole to form a balance channel. In particular, the extension direction of the section is the same as the axial direction of the guide seat 30, i.e. the balancing passage 40 preferably extends in a vertical direction, in order to better balance the pressure between the receiving chamber 11 and the valve chamber 12.

Specifically, the limiting boss 31 includes a first boss 311 and a second boss 312 which are arranged in a stepped manner, the first boss 311 is arranged corresponding to the first hole 141, and the second boss 312 is arranged corresponding to the second hole 142. The first boss 311 and the first hole 141 are in interference fit, and the second boss 312 and the second hole 142 are in interference fit, transition fit or clearance fit. The notch 41 penetrates through the first boss 311 and the second boss 312, so that a gap exists between the limiting boss 31 and the mounting hole, thereby forming a balance passage.

In this embodiment, a plurality of notches 41 are provided on the side wall of the guide holder 30, and the plurality of notches 41 are provided at intervals along the circumferential direction of the limit boss 31. Specifically, two tangent planes are arranged on the side wall of the guide seat 30, the two tangent planes penetrate through the first boss 311 and the second boss 312, and the tangent planes on the two sides are symmetrically arranged along the circumferential direction of the limiting boss 31 at intervals. In other embodiments, the number of the notches 41 may be changed according to the use situation, and the number of the notches 41 may be three, four, five, and the like.

As shown in fig. 5 to 10, according to the second embodiment of the present invention, there is provided an electronic expansion valve, which is different from the first embodiment in that the guide seat 30 and/or the valve seat 14 have a communication hole 42, one end of the communication hole 42 communicates with the accommodation chamber 11, the other end of the communication hole 42 communicates with the valve chamber 12, and the communication hole 42 forms the balancing passage 40. In the present embodiment, the communication hole 42 is provided on the guide holder 30. In other embodiments, the communication hole 42 may be provided on the valve seat 14. Specifically, by providing a cut groove on the inner wall of the valve seat, the balance passage can be formed by the cut groove.

As shown in fig. 7, a communication hole 42 is provided on the stopper boss 31, one end of the communication hole 42 communicates with the housing chamber 11, and the other end of the communication hole 42 communicates with the second hole 142, so that the communication hole 42 can communicate with the valve chamber 12 through the notch 41. In the present embodiment, the outer diameter of the second boss 312 is smaller than the diameter of the second hole 142, so that a gap is formed between the second boss 312 and the second hole 142. Specifically, one end of the communication hole 42 communicates with the housing chamber 11, and the other end of the communication hole 42 communicates with the valve chamber 12 through a gap between the second boss 312 and the second hole 142.

As shown in fig. 10, a communication hole 42 is provided on the inner wall of the valve seat 14, the communication hole 42 is provided through the mounting hole such that one end of the communication hole 42 communicates with the housing chamber 11, and the other end of the communication hole 42 communicates with the second hole 142, thereby making it possible to communicate the communication hole 42 with the valve chamber 12 through the notch 41.

In the present embodiment, the guide holder 30 has a plurality of communication holes 42, and the plurality of communication holes 42 are provided at intervals in the circumferential direction of the guide holder 30 on the stopper boss 31. Specifically, the guide holder 30 has two communication holes 42, and the two communication holes 42 are symmetrically arranged at intervals in the circumferential direction of the guide holder 30. In other embodiments, the number of the communication holes 42 may be changed according to the use, and the number of the communication holes 42 may be three, four, five, and the like.

Specifically, the nominal diameter of the unilateral balance channel is 0.5-3 mm. When the first embodiment is adopted and the notches 41 are formed in the side wall of the guide seat 30, so that the plurality of notches form the balance channel, the area of the notch on one side is measured, the notch is converted into a circular hole with the same area, and the diameter of the circular hole is the nominal diameter of the balance channel on one side. When the communicating hole 42 is provided in the guide seat 30 and/or the valve seat 14 as provided in the second embodiment so that the communicating hole 42 forms the equilibrium channel, the diameter of the communicating hole 42 on one side is the nominal diameter of the equilibrium channel on one side.

In the present embodiment, the valve core assembly 20 includes a rotor 21, a nut seat 22, a screw 23, and a valve needle assembly 24. Wherein, the rotor 21 can be rotatablely arranged in the containing cavity, and the nut seat 22 is fixedly arranged in the containing cavity. Specifically, the rotor 21 is in driving connection with one end of a screw 23, the needle assembly 24 is connected with the other end of the screw 23, the screw 23 is inserted into the nut seat 22, and the screw 23 is in threaded fit with the nut seat 22. When the electronic expansion valve is opened or closed, the rotor 21 is rotated in the accommodating cavity, and the rotor 21 drives the screw 23 to rotate relative to the nut seat 22, so that the screw 23 adjusts the relative position of the valve needle assembly 24 and the valve port, thereby opening or closing the electronic expansion valve.

One end of the guide seat 30 is connected with the valve seat 14, the other end of the guide seat 30 is connected with the nut seat 22, and the excircle of the guide seat 30 is in transition fit or interference fit with the inner hole of the nut seat 22, so that the nut seat 22 is guided and corrected, and the coaxiality of the nut seat 22 and the valve seat 14 is improved. Specifically, the guide seat 30 has a connecting section and a limiting section which are oppositely arranged, and the limiting boss 31 is arranged on the limiting section. Wherein, the connecting section is inserted into the nut seat 22 in an interference fit manner to realize the fixed connection of the guide seat 30 and the nut seat 22. Specifically, the guide seat 30 has a guide hole provided at the connecting section and extending in the same direction as the axial direction of the guide seat 30, and the needle assembly 24 is movably disposed in the guide hole. With the above configuration, the guide seat 30 is provided between the nut seat 22 and the valve seat 14, so that the guide seat 30 can guide the multiple needle assemblies 24, thereby ensuring the coaxiality between the nut seat 22, the needle assemblies 24, and the valve seat 14.

The needle assembly 24 includes a needle and a preloaded spring. The first end of the valve needle is arranged towards the valve port, the second end of the valve needle is connected with the screw rod 23, the pre-tightening spring is arranged between the valve needle and the screw rod 23, and the pre-tightening spring is used for providing pre-tightening force for the valve needle. And when the valve needle is abutted to the valve port, the pre-tightening spring can reduce the impact force between the valve needle and the valve port, and can be opened under a certain pressure difference during reverse flow, so that the valve needle, the valve port and a system can be protected.

By providing the notch 41 on the side wall of the guide seat 30 or providing the communication hole 42 on the guide seat 30 and/or the valve seat 14, a balance passage 40 can be provided between the accommodating chamber 11 and the valve chamber 12, and when the electronic expansion valve is opened or closed, the accommodating chamber 11 and the valve chamber 12 can realize rapid pressure balance through the balance passage 40, so that the components in the housing 10 are not damaged, and the service life of the expansion valve can be prolonged.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc. are usually based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and in the case of not making a reverse description, these orientation words do not indicate and imply that the device or element being referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore, should not be considered as limiting the scope of the present invention; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electronic expansion valve, comprising:

the valve comprises a shell (10), wherein the shell (10) is provided with a containing cavity (11) and a valve cavity (12), the containing cavity (11) and the valve cavity (12) are arranged at intervals, the valve cavity (12) is used for being communicated with a pipeline, the shell (10) comprises a valve seat (14), and the valve cavity (12) is arranged in the valve seat (14);

the valve core assembly (20) is movably arranged in the shell (10), the valve core assembly (20) is provided with an opening position and a blocking position, when the valve core assembly (20) is located at the opening position, the valve cavity (12) is in a conducting state, and when the valve core assembly (20) is located at the blocking position, the valve cavity (12) is in a blocking state;

the guide seat (30) is arranged in the shell (10), the guide seat is located between the accommodating cavity (11) and the valve cavity (12), the valve core assembly (20) is partially arranged in the guide seat (30) in a penetrating mode, a balance channel (40) is arranged between the guide seat (30) and the valve seat (14), one end of the balance channel (40) is communicated with the accommodating cavity (11), and the other end of the balance channel (40) is communicated with the valve cavity (12).

2. An electronic expansion valve according to claim 1, wherein the housing (10) further comprises a sleeve (13), the valve seat (14) is connected to the sleeve (13), one end of the valve seat (14) adjacent to the sleeve (13) has a mounting hole, the mounting hole communicates with the sleeve (13) to form the accommodating chamber (11), the valve chamber (12) is disposed at the other end of the valve seat (14), and the guide seat (30) is fixedly connected to the valve seat (14) through the mounting hole.

3. The electronic expansion valve according to claim 2, wherein the mounting holes are stepped holes, the mounting holes comprise a first hole (141) and a second hole (142) which are arranged in sequence and have successively smaller diameters, and the second hole (142) is communicated with the valve chamber (12).

4. An electronic expansion valve according to claim 3, wherein a limiting boss (31) is provided on an outer wall of the guide seat (30), the limiting boss (31) is in interference fit with the first hole (141), the limiting boss (31) is used for limiting a relative position of the guide seat (30) and the valve seat (14), and the guide seat (30) is inserted into the first hole (141) and the second hole (142).

5. An electronic expansion valve according to claim 4, wherein the balancing passage (40) comprises a notch (41), the notch (41) being provided in a side wall of the stop boss (31), the accommodation chamber (11) communicating with the valve chamber (12) through the notch (41).

6. An electronic expansion valve according to claim 5, wherein the limiting projection (31) comprises a first projection (311) and a second projection (312) arranged in a step, the first projection (311) is arranged corresponding to the first hole (141), the second projection (312) is arranged corresponding to the second hole (142), and the notch (41) extends through the first projection (311) and the second projection (312).

7. An electronic expansion valve according to claim 5, wherein a plurality of said notches (41) are provided in a side wall of the guide seat (30), and a plurality of said notches (41) are provided at intervals in a circumferential direction of the stopper boss (31).

8. An electronic expansion valve according to claim 4, wherein the guide seat (30) and/or the valve seat (14) has a communication hole (42), one end of the communication hole (42) communicating with the accommodation chamber (11), the other end of the communication hole (42) communicating with the valve chamber (12), the communication hole (42) forming the equilibrium channel (40).

9. An electronic expansion valve according to claim 8, wherein the communication hole (42) is provided on the stopper boss (31), one end of the communication hole (42) communicates with the accommodation chamber (11), and the other end of the communication hole (42) communicates with the second hole (142).

10. An electronic expansion valve according to claim 9, wherein the guide seat (30) has a plurality of the communication holes (42), and the plurality of the communication holes (42) are provided on the stopper boss (31) at intervals in a circumferential direction of the guide seat (30).